Mesozoic plate subduction in West Pacific and tectono-magmatic response in the East Asian ocean-continent connection zone

Abstract

The Mesozoic impact to the North China and the South China blocks in the East Asian Continental Margin by the West Pacific subduction processes and deep processes, the tectonic, magmatic mineralization and geomorphic evolutionary trends show some similarities, but there are also significant differences beween them, the dynamic mechanism is generally believed to be caused by the Paleo-Pacific Plate subduction. But how they are related is a long-term unresolved question as a conundrum and a focus of geological researches, and a huge controversy is still remained. This paper systematically summarizes the comprehensive achievements of deformation analysis, igneous geochronology, tomography and other field observations in the East Asian Continental Margin in recent decade, briefly discussing the pre-Yanshanian final assembly of blocks and the formation of the unified continental margin in China, and mainly focusing on the review of Jurassic and Cretaceous geological processes in the East Asian Ocean-Continent Connection Zone in the Yanshanian period. The temporal and spatial evolution of structural propagation, age zonation and migration of igneous rocks and huge tectono-morphological inversion in the Earth surface system, combined with deep processes are jointly to put forward: the destruction of the North China Craton was mainly affected by the westard early-stage layerred rollback, delamination and thinning of the deep lithosphere, resulting in early Yanshanian westward migration of tectonism and magmatism following the middle-stage multiple-directional delamination and the late-stage eastward withdrawal of delamination; coevally, the combined effect of the closure of the Okhotsk Ocean to the north and the subduction of the Bangong-Co-Nujiang Ocean to the south made the East Asian Ocean-Continent Connection Zone under the tectonic setting of overall compression, the asthenosphere upwelling at depth continued an eastward migration to drive lithosphere continuously eastward and periodical, alternative extension and compression. The South China Block experienced the westward flat subduction at early stage, resulting in the westward propagation of deformation and magmatism, following the late two-stage delamination to induce the eastward tectono-magmatism. In summary, the tectono-magmatic differences between the North China and South China blocks are caused by their difference of the deep mantle processes and the East Asian plate superconvergence.